Safety switch having visible movable contact



Oct. 19, 1965 s. A. MRENNA 3,213,252

SAFETY SWITCH HAVING VISIBLE MOVABLE CONTACT Filed March 16, 1962 2 Sheets-Sheet l Fig.|.

Fig.5.

I l 63 l 1 67 66 L l3 WITNESSES INVENTOR Stephen A. Mrenno ATTORNEY s. A. MRENNA 3,213,252

SAFETY SWITCH HAVING VISIBLE MOVABLE CONTACT Oct. 19, 1965 2 Sheets-Sheet 2 Filed March 16. 1962 United States Patent Pa., assignor to Westinghouse Electric Corporation,

East Pittsburgh, Pa., a corporation of Pennsylvania Filed Mar. 16, 1962, Ser. No. 180,208 4 Claims. (Cl. 200-163) This invention relates to electric control devices and more particularly to electric control devices of the type known in the art as safety switches.

At a safety switch installation, it is sometimes desirable for an authorized worker to operate the switch or to inspect and service the switch when the enclosure cover is open. In the interests of safety and worker-confidence, it is desirable to provide a safety switch that is so constructed that the contact positions are readily apparent when the enclosure cover is open.

Accordingly, an object of this invention is to provide an improved safety switch that is so constructed that the open or closed position of the movable contact is clearly visible when the enclosure cover is open.

Another object of this invention is to provide an improved compactly constructed safety switch.

A further object of this invention is to provide an improved safety switch comprising modular units that can readily be added to or subtracted from in order to fulfill certain control requirements.

The invention, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description thereof when read in conjunction with the accompanying drawings.

In said drawings:

FIGURE 1 is a plan view, with the enclosure cover partly broken away, of a safety switch constructed in accordance with certain principles of this invention;

FIG. 2 is a sectional view taken substantially along the line 11-11 of FIG. 1;

FIG. 3 is a partial view similar to FIG. 2 showing parts of the switch in the closed position;

FIG. 4 is a partial sectional view of one of the modular unit-s of the safety switch;

FIG. 5 is a plan view of the neutral strap seen in FIG. 1;

FIG. 6 is a view similar to FIG. 1 illustrating a safety switch constructed in accordance with certain principles of this invention and comprising three pole units. V

Referring to the drawings, and particularly to FIG. 1, a safety switch 5 comprises an enclosure 7 having a switch structure 9 therein, which switch structure 9 is operated by means of a common operating mechanism 11.

The enclosure 7 comprises a base 13, four side walls and an openable cover 17 disposed opposite the base 13 and pivotally supported on one of the sidewalls 15 by means of hinges 19. Standard type knockouts 20 are provided in the enclosure base and sidewalls. These knockouts are removable to provide openings for receiving conductors that are used to connect the safety switch in an electric circuit.

The switch structure 9 comprises two modular pole units 21 and 23 disposed in a substantially abutting sideby-side relationship. Each of the pole units 21 and 23 comprises a block of insulating material 25 supported on the base 7 of the enclosure by means of two screws 27. As best seen in FIG. 4, -a conducting strap 31 is supported on each of the insulating blocks 25 by means of a rivet 33 that also secures a conductor 35, an insulating member 37 and a fuse socket 39 to the insulating block 25. A

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screw 41 is provided at one end of each of the conductors 31 to enable connection of the pole units in an electrical circuit. A contact portion 43 disposed at one end of each conductor 35 cooperates with a contact portion 45 that is disposed at one end of a conductor 47 to form a clip type stationary contactstructure 43, 45. Each of the conductors 47 is secured to the associated insulated block 25 by means of a rivet 49. A screw 51 is provided at the outer end of each conductor 47 to enable connection of the associated pole unit in an electrical circuit. A movable contact structure 53 that comprises a flat sheet of insulating material 55 having a movable contact 57 secured thereto at its upper end, cooperates with each of the stationary contact structures 43, 45 to open and close an electric circuit.

The movable contact structures 53 of both of the pole units 21 and 23 (FIG. 1) are manually operated to the open (FIG. 2) and closed (FIGS. 3 and 4) positions by means of the common operating mechanism 11 which comprises a crank arm 61 having two looped portions 63 (FIG. 1) each of which looped portions engages in slots 65 (FIGS. 2, 3 and 4) on opposite sides of one of the insulating members 55 to operatively connect the movable Contact structures 53 to the common crank arm 61. The crank arm 61 is pivotally supported at 66 in a bracket 67 that is secured to one of the enclosure side walls 15 by means of a rivet 69. The other end of the crank arm 61 is pivotally supported in a suitable opening in the opposite side wall 15. In addition to the common crank arm 61, the operating structure 11 comprises an operating lever 73 that is pivotally supported on the bracket 67 by means of a pivot pin 75. The operating lever 73 is operatively connected to the crank arm 61 by means of a portion 79 thereof having a slot 81 therein that receives a bent-over end 82 of an arm 83 of the crank arm '61. As seen in FIGS. 2 and 3, a portion of the operating lever 73 extends out through an opening 85 in the enclosure cover 17, a handle 87 is disposed at the outer end of the lever 73 for manual operation of the switch structure 9.

When the contact structures 53 are in the closed position seen in FIGS. 3 and 4, the circuit through each of the modular pole units 21 and 23 extends from the conductor 31, through the fused socket 39, a standard screwin type fuse that would be disposed in the socket 39 when the switch is in operating condition, the conductor 35, the stationary contact 43, the movable contact 57, the stationary contact 45, through the conductor 47. In order to more clearly show the parts of the switch structure, fuses are not shown in the drawings'in the sockets 39. It can be understood, however, that when the switch is in operation, standard screw-in type fuses would be properly disposed within the sockets 39.

The safety switch 5 is shown in the open position in FIGS. 1 and 2. When it is desired to close the switch, the operating lever 73 is rotated clockwise (FIG. 2) about the pivot to the closed position seen in FIG. 3. This movement rotates the crank arm 61 clockwise about the pivot 66 which movement, by virtue of the connection between the looped portions 63 of the crank arm 61 and the insulating members 55 of the movable contact structures 53, moves both of the movable contact structures 53 rectilinearly downward to the closed position seen in FIGS. 3 and 4.

As seen in FIGS. 2 and 3, the slot 81 is provided in the portion 79 of the operating member 73 in order to permit the transfer of motion between the operating member 73 which is pivoted at 75 and the crank arm 61 which is pivoted on a separate pivot at 66. Thus, during the closing and opening movements of the operating '3 member 73, the arm 83 of the crank arm 61 moves from one to the other end of the slot 81.

The safety switch is manually opened by counterclockwise movement of the operating member 73 from the closed (FIG. 3) to the open (FIG. 2) position. This movement, moves the crank arm 61 counterclockwise about the pivot 66 to rectilinearly move the movable contact structures 53 upward toward the opening or front of the enclosure 7 to the open position seen in FIG. 2. When the movable contact structure 53 is moved up to the open position, the insulating part 55 thereof moves between the contacts 43 and 45 to extinguish the arcs generated between the contact 57 and the contacts 43 and 45.

The rectilinear movement of the movable contact structure 53 to the open and closed positions is guided by engagement of the insulating member 55 with side walls of an opening 89 in each of the insulating blocks 25. Each of the openings 89 is small enough so that the side walls thereof form a track to guide the rectilinear movement of the associated contact structure 53.

It is to be noted that the movable contact structures 53 are each moved endwise and rectilinearly along a plane that is generally perpendicular to the flat base 13 of the housing 7, and that when the switch is in the open position, the movable contacts 57 are positioned out at the front of the switch where they are readily visible to a worker that would be operating the switch or inspecting the parts thereof when the enclosure cover 17 is in the open position. It is also to be noted that the particular construction of the switch structure 9 is compact and that for some applications, when it is desired to save plant space, the switch structure 9 can be disposed in an enclosure considerably smaller than the enclosure 7 that is seen in FIGS. 1-3.

Each of the insulating blocks 25 has a recessed shelf portion 91 (FIGS. 1 and 2) thereon. Thus, when the safety switch 5 is used in a distribution system wherein a neutral conductor is used, a neutral conductor 93 (FIG. 5) can be mounted on one of the shelf portions 91 of one of the insulating blocks 25.

As seen in FIG. 1, the neutral conductor 93 is mounted on the recessed shelf 91 of the upper insulating block 25. The neutral conductor 93 has a screw 95 disposed at each end thereof for electrical connection of the conductor 93 to leads (not shown) that would engage in the slots 96 disposed in the strap 93. A screw member 97 is provided for connecting the conductor 93 to a ground lead that would be disposed in the transverse slot 99 in the conductor 93. v

As seen in FIG. 6, since the insulating blocks of the separate pole units are identical in construction and separate from each other, a three pole switch 105 is provided by merely mounting an additional modular pole unit 125 alongside of the units 21 and 23. The parts of the safety switch 105 seen in FIG. 6 that are similar to the parts of the safety switch 5 seen in FIG. 1, have reference characters applied thereto that are identical to the reference characters of the similar parts of the safety switch 5. As seen in FIG. 6, a neutral conductor 93 is disposed on the recessed shelf portion 91 of the upper insulating block 25. As seen in FIG. 6, the cabinet or enclosure 7 is enlarged widthwise to accommodate the additional pole unit 125, and the crank arm 61 is lengthened and provided with three loop portions 63 for operating the three movable contact structures 53 of the safety switch 105. The safety switch 105 (FIG. 6) is operated in the same manner as the safety switch 5.

From the foregoing, it is apparent that there is provided by this invention a safety switch that is so constructed that the open and closed positions of the movable contacts are clearly visible when the enclosure cover is in the open position. The switch is compactedly constructed and easily assembled to provide savings in manufacturing costs. The safety switch is made up of modular units each having a shelf portion to receive a neutral conductor. The modular units can be added to or subtracted from in order to provide different types of multipole switches.

Since numerous changes may be made in the above described construction, and additional embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. An electric control device comprising, in combination, an enclosure comprising a generally planar base and side walls extending upward from said base to form an opening, a cover movable to open and close said opening, a switch structure disposed within said enclosure and comprising a stationary contact structure, said stationary contact structure comprising a first contact and a second contact spaced from said first contact, a contact carrier comprising a generally fiat member of insulating material supported within said enclosure with the generally flat sides thereof being disposed along planes that are generally normal to the plane of said base, a movable contact fixedly supported on the upper end of said contact carrier, in the closed position, said movable contact being disposed between and in engagement with said first and second contacts, and operating means operable to rectilinearly move said contact carrier toward said opening to move said movable contact away from said stationary contact structure during which movement said insulating member moves between said first and second contacts.

2. An electric control device comprising, in combination, an enclosure comprising a generally planar base and side walls extending upward from said base to form an opening, a cover movable to open and close said opening, a switch structure disposed within said enclosure and comprising a stationary contact structure, said stationary contact structure comprising a first contact and a second contact separated from said first contact, a contact carrier comprising a generally fiat member of insulating material supported within said enclosure with the generally flat planes thereof being generally normal to the plane of said base, a movable contact comprising two generally parallel leg portions and a bight portion connecting said leg portions, said movable contact being supported on the upper end of said contact carrier with said leg portions being disposed on opposite sides of said contact carrier and said bight portion being disposed over the upper end of said contact carrier, in the closed position said movable contact being disposed between and in engagement with said first and second contacts, and operating means operable to move said contact carrier rectilinearly toward said opening and in a direction generally normal to the plane of said base to move said movable contact to an open position out of engagement with said first and second contacts.

3. An electric control device according to claim 1 wherein said operating means comprises a crank-arm and an operating member, said crank-arm being rotatable about a first axis that extends generally parallel to the plane of said base to operatively move said contact carrier, said operating member being rotatable about a second axis that extends generally parallel to the plane of said base which second axis is disposed between said first axis and said opening, lost-motion connecting means cone, 2 1 3, 2 5 2 5 6 plane of said base, said operating member being rotatable References Cited by the Examiner about a second axis that extends generally parallel to I 4 the plane of said base which second axis is disposed be- UN TED STATES PATENTS tween said first axis and said opening, means operatively 1,889,515 11/32 Hammerly ZOO-163 connecting said crank-arm with said contact carrier, lost- 5 1394543 1/33 Rowe 200 163 motion connecting means operatively connecting said op- 21004329 6/35 Johansson 200163 crating member with said crank-arm, and said operating member being rotatable to rotate said crank-arm to BERNARD GILHEANY Prmmry Exammer thereby operatively move said contact carrier. ROBERT K. SCHAEFER, Examiner. 

1. AN ELECTRICAL CONTROL DEVICE COMPRISING, IN COMBINATION, AN ENCLOSURE COMPRISING A GENERALLY PLANAR BASE AND SIDE WALLS EXTENDING UPWARD FROM SAID BASE TO FORM AN OPENING, A COVER MOVABLE TO OPEN AND CLOSE SAID OPENING, A SWITCH STRUCTURE DISPOSED WITHIN SAID ENCLOSURE AND COMPRISING A STATIONARY CONTACT STRUCTURE, SAID STATIONARY CONTACT STRUCTURE COMPRISING A FIRST CONTACT AND A SECOND CONTACT SPACED FROM SAID FIRST CONTACT, A SECOND CARRIER COMPRISING A GENERALLY FLAT MEMBER OF INSULATING MATERIAL SUPPORTED WITHIN SAID ENCLOSURE WITH THE GENERALLY FLAT SIDES THEREOF BEING DISPOSED ALONG PLATES THAT ARE GENERALLY NORMAL TO THE PLANE OF SAID BASE, A MOVABLE CONTACT FIXEDLY SUPPORTED ON THE UPPER END OF SAID CONTACT CARRIER, IN THE CLOSED POSITION, SAID MOVABLE CONTACT BEING DISPOSED BETWEEN SAID IN ENGAGEMENT WITH SAID FIRST AND SECOND CONTACTS, AND OPERATING MEANS OPERABLE TO RECTILINEARLY MOVE SAID CONTACT CARRIER TOWARD SAID OPENING TO MOVE SAID MOVABLE CONTACT AWAY FROM SAID STATIONARY CONTACT STRUCTURE DURING WHICH MOVEMENT SAID INSULATING MEMBER MOVES BETWEEN SAID FIRST AND SECOND CONTACTS. 